Tuesday, May 1, 2012

Bismuth‘s Production

The most important ores of bismuth are bismuthinite and bismite.[5] In 2005, China was the top producer of bismuth, with at least 40% of the world share followed by Mexico and Peru, reports the British Geological Survey. Native bismuth is known from Australia, Bolivia, and China.
According to the United States Geological Survey, world 2009 mine production of bismuth was 7,300 tonnes, with the major contributions from China (4,500 tonnes), Mexico (1,200 tonnes) and Peru (960 tonnes). World 2008 bismuth refinery production was 15,000 tonnes, of which China produced 78%, Mexico 8% and Belgium 5%.
bismuth (Bi)The difference between world bismuth mine production and refinery production reflects bismuth's status as a byproduct metal. Bismuth travels in crude lead bullion (which can contain up to 10% bismuth) through several stages of refining, until it is removed by the Kroll-Betterton process or the Betts process. The Kroll-Betterton process uses a pyrometallurgical separation from molten lead of calcium-magnesium-bismuth drosses containing associated metals (silver, gold, zinc, some lead, copper, tellurium, and arsenic). The Betts process takes cast anodes of lead bullion and electrolyzes them in a lead fluorosilicate-hydrofluorosilicic acid electrolyte to yield a pure lead cathode and an anode slime containing bismuth. Bismuth will behave similarly with another of its major metals, copper.
The raw bismuth metal from both process contains still considerable amounts of other metals foremost lead. By reacting the molten mixture with chlorine gas the metals are converted to their chlorides while bismuth remains unchanged. Impurities can also be removed by various other methods for example with fluxes and treatments yielding high-purity bismuth metal (over 99% Bi). World bismuth production from refineries is a more complete and reliable statistic.
According to the Bismuth Advocate News, the price for bismuth metal from year-end 2000 to September 2005 ranged from $2.60 to $4.15 per pound, but after this period the price started rising rapidly as global bismuth demand as a lead replacement and other uses grew rapidly. New mines in Canada and Vietnam may relieve the shortages, but prices are likely to remain above their previous level for the foreseeable future. The customer-input price for bismuth is more oriented to the ultimate consumer; it started at US$39.40 per kilogram ($17.90 per pound) in January 2008 and reached US$35.55 per kg (US$16.15 per lb.) in September 2008.


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